Objective To observe whether calreticulin-induced mitochondrial dysfunction is involved in cardiomyocyte hypertrophy induced by angiotensin Ⅱ (AngⅡ).Methods Primary culture of neonatal rat cardiomyocytes was further confirmed by immunocytochemistry.The cardiomyocytes were randomly divided into model group,valsartan group and control group.The model group was subdivided into three groups which were separately treated with 1 0-8 mmol/L, 1 0-7 mmol/L, and 1 0-6 mmol/L Ang Ⅱ. Calreticulin expression, mitochondrial membrane potential level, enzyme activities, cell surface area and protein synthesis rate were observed.Results Cell surface area and protein synthesis rate were both increased in model groups compared with control group.Mitochondrial membrane potential level and enzyme activities were lower in model groups than in control group,while calreticulin expression was up-regulated.Pretreatment with valsartan partially reversed all the above changes.Conclusion Mitochondrial dysfunction induced by calreticulin may be an important mechanism of myocardial hypertrophy.

Expression of c-fos protein in the medulla oblongata after baroreceptor activation by elevated intrasinus pressure (ISP) and perfusion of adenosine (Ado) was examined in 14 vascularly isolated carotid sinus perfusion rats. The results showed that Fos-like immunoreactive(FLI) neurons were distributed throughout nucleus tractus solitarius, area postrema, rostral ventrolateral medulla and nucleus raphe pallidus, and the number of FLI was increased with the elevation of ISP. Furthermore, perfusing the carotid sinus with Ado at a given ISP markedly increased the FLI in the above regions. From the results obtained, it is concluded that the c-fos expression in baroreflex pathway in medulla oblongata may be enhanced by elevated ISP and intrasinus perfusion of Ado, and Ado is capable of facilitating the baroreflex.

This study was purposed to investigate the effect of 3'-azido-2', 3'-dideoxythymidine (AZT)on the proliferation and telomerase activity of human acute myeloid leukemia cell line KG-1a. The effect of proliferation was detected by MTT assay after the KG-1a cell were stimulated for 24, 48 and 72 h with different concentrations of AZT; telomerase activity was detected with TRAP-PCR-ELISA assay; RT-PCR was used to detect telomerase hTERT mRNA expression. The results showed that the proliferation of KG-1a cells was inhibited in a time and concentration dependent manner after exposure to AZT for 24, 48 and 72 h; the KG-1a cells decreased in S phase and increased in G(2)/M phase with the increasing of the concentration of AZT; telomerase activity and hTERT-mRNA expression in the experimental groups decreased after treated with AZT, which was positively correlated with concentration of AZT. It is concluded that AZT inhibits KG-1a cell proliferation and induces apoptosis, which maybe related with its decreasing the telomerase activity and hTERT mRNA expression.
Apoptosis ; drug effects ; Cell Cycle ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Humans ; Leukemia ; metabolism ; pathology ; Telomerase ; antagonists & inhibitors ; metabolism ; Zidovudine ; pharmacology

Using two-kidney one-clip renal hypertensive (2K1C group), stress-induced hypertensive (neural group), DOCA-salt treated hypertensive (DOCA group) and spontaneously hypertensive rats (SHR group), to investigate the change in AT(1A)-receptor autoantibodies (AT(1A)-AAs) during the development of the four types of hypertension. The biological activities of AT(1A)-AAs were examined. It was shown that the frequency of occurrence and titres of AT(1A)-AAs increased significantly during the development of hypertension. In the four hypertensive groups studied, the occurrence of AT(1A)-AAs was most prominent in SHR, 2K1C and neural groups. The biological effects of AT(1A)-AAs were shown to increase the beating frequency of cultured neonatal myocardial and vascular contractile tension. It is suggested that autoimmune mechanisms are involved the pathogenesis of different types of hypertension and the AT(1A)-AAs may be one of the mechanisms leading to cardiac hypertrophy.
Animals ; Autoantibodies ; blood ; Desoxycorticosterone ; administration & dosage ; Hypertension ; classification ; etiology ; immunology ; physiopathology ; Hypertension, Renovascular ; immunology ; physiopathology ; Male ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY ; Rats, Wistar ; Receptor, Angiotensin, Type 1 ; immunology ; Stress, Physiological ; physiology

Objective To investigate the reversal effect of MDR1 and MDR3 gene silencing on resistance of A2780/taxol cells to paclitaxel.Methods shRNA plasmid vector specifically targeting MDR1 and MDR3 genes was transfected into A2780/taxol cells.The early stage cell apoptosis and the effect of intracellular rhodamine 123(Rh123)accumulation were detected by flow cytometry(FCM).The late stage cell apoptosis rate was detected by terminal deoxynucleotidyl transferase(TdT)-mediated deoxyuridine triphosphate(dUTP)nick end labeling(TUNEL).The 50% inhibition concentration(IC_(50))of paclitaxel on A2780/taxol cells was determined by methyl thiazolyl tetrazolium(MTT)assay.MDR1 and MDR3 mRNA were assessed by RT-PCR,and caspase-3 protein was detected by western blot.Results After treatment with MDR1 and MDR3 shRNA plasmid vector,early apoptosis rate of A2780/taxol cells was (20.21?0.56)% and(10.87?1.24)%,respectively.MDR1 and MDR3 shRNA could increase cellular Rh123 accumulation(116.6?8.1 and 98.4?3.8,respectively).The late stage apoptosis rates detected by TUNEL displayed the same tendency as FCM results did.The IC_(50)for paclitaxel of A2780/taxol cells was decreased significantly.The mRNA levels of MDR1 and MDR3 in A2780/taxol cells were decreased by (73.3?0.8)% and(51.6?0.4)% of control,and the reduction of MDR1 and MDR3 mRNA was in a time-dependent manner.The expression of caspase-3 protein of MDR1 and MDR3 shRNA vector transfected group in A2780/taxol cells was significantly increased [(80.8?2.6)% and(72.0?4.7)%, respectively ].Conclusion MDR1 and MDR3 gene silencing could recover sensitivity of A2780/taxol cells to paclitaxel and induce cell apoptosis,thus reversing cell resistance to paclitaxel.

OBJECTIVETo investigate the effect of Astragalus membranaceus (AM) on endothelial-dependent (EDV) and non- dependent (EIV) vascular relaxation in ex vivo thoracic aortic rings of obese rats.

METHODSFifteen SD rats were randomized into 3 equal groups, namely the control group fed with normal chow, obese group with high-fat chow, and AM intervention group fed with high-fat chow and daily AM gavage. The rats were sacrificed after 6 weeks of feeding, and the aortic rings were dissected and cut into 3-mm rings. The response to acethylcholine (Ach) and sodium nitroprusside (SNP) were examined in organ bath. In ex vivo study, the aortic rings obtained from the control group and obese group were incubated with AM or vehicle for 3 h in organ bath before testing the EDV and EIV. The body weight and weight of the visceral fat in each group were recorded.

RESULTSThe weight of visceral fat was greater in the obese group than in the control group, and a 6-week AM treatment significantly reduced the fat tissue due to high-fat diet. The maximum EDV value was (87.0 - or + 3.5)% in the control group, (54.8 - or + 7.8)% in the obese group, and (69.8 - or + 5.7)% in AM intervention group; the EIV values were comparable between the 3 groups. After incubation with AM, the maximum EDV values of aortic rings obtained from the obese group were significantly increased from (55.6 - or + 8.3)% to (85.1 - or + 4.5)%.

CONCLUSIONAM can improve endothelial dysfunction in obese rats, and the mechanism involves improved insulin resistance and increased endothelium-derived NO productor function.

Animals ; Aorta, Thoracic ; pathology ; Astragalus membranaceus ; chemistry ; Drugs, Chinese Herbal ; pharmacology ; Endothelium, Vascular ; drug effects ; pathology ; physiopathology ; Endothelium-Dependent Relaxing Factors ; therapeutic use ; In Vitro Techniques ; Insulin Resistance ; Male ; Obesity ; physiopathology ; Phytotherapy ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Vasodilator Agents ; pharmacology

To study the electrophysiological effects of capsaicin on spontaneous activity of rabbit atrioventricular (AV) node cells, parameters of action potential in AV node were recorded using intracellular microelectrode technique. Capsaicin (1-30 micromol/L) not only decreased the amplitude of action potential, maximal rate of depolarization (V(max)), velocity of diastolic (phase 4) depolarization, and rate of pacemaker firing, but also prolonged the duration of 90% repolarization of action potential (APD(90)) in a concentration-dependent manner. Both application of L-type Ca(2+) channel agonist Bay K8644 (0.5 micromol/L) and elevation of calcium concentration (5 mmol/L) in superfusate antagonized the effects of capsaicin on pacemaker cells. Pretreatment with ruthenium red (10 micromol/L), a capsaicin receptor blocker, did not affect the effects of capsaicin on AV node cells. Capsaicin exerted an inhibitory action on spontaneous activity of AV node cells in rabbits. These effects were likely due to reduction in calcium influx, but were not mediated by VR1.
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester ; pharmacology ; Action Potentials ; drug effects ; Animals ; Atrioventricular Node ; cytology ; physiology ; Calcium ; metabolism ; Calcium Channel Agonists ; pharmacology ; Calcium Channels, L-Type ; drug effects ; Capsaicin ; pharmacology ; Male ; Microelectrodes ; Rabbits ; Receptors, Drug ; antagonists & inhibitors ; Ruthenium Red ; pharmacology

This study examined the protective effect of ischemic postconditioning (IPoC) and minocycline postconditioning (MT) on myocardial ischemia-reperfusion (I/R) injury in atherosclerosis (AS) animals and the possible mechanism. Forty male healthy rabbits were injected with bovine serum albumin following feeding on a high fat diet for 6 weeks to establish AS model. AS rabbits were randomly divided into 3 groups: (1) I/R group, the rabbits were subjected to myocardial ischemia for 35 min and then reperfusion for 12 h; (2) IPoC group, the myocardial ischemia lasted for 35 min, and then reperfusion for 20 s and ischemia for 20 s [a total of 3 cycles (R20s/I20s×3)], and then reperfusion was sustained for 12 h; (3) MT group, minocycline was intravenously injected 10 min before reperfusion. The blood lipids, malondialdehyde (MDA), superoxide dismutase (SOD), soluble cell adhesion molecule (sICAM), myeloperoxidase (MPO), and cardiac troponin T (cTnT) were biochemically determined. The myocardial infarction size (IS) and apoptosis index (AI) were measured by pathological examination. The expression of bcl-2 and caspase-3 was detected in the myocardial tissue by using reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the AS models were successfully established. The myocardial IS, the plasma levels of MDA, sICAM, MPO and cTnT, and the enzymatic activity of MPO were significantly decreased, and the plasma SOD activity was significantly increased in IPoC group and MT group as compared with I/R group (P<0.05 for all). The myocardial AI and the caspase-3 mRNA expression were lower and the bcl-2 mRNA expression was higher in IPoC and MT groups than those in I/R group (all P<0.05). It is concluded that the IPoC and MT can effectively reduce the I/R injury in the AS rabbits, and the mechanisms involved anti-oxidation, anti-inflammation, up-regulation of bcl-2 expression and down-regulation of caspase-3 expression. Minocycline can be used as an effective pharmacologic postconditioning drug to protect myocardia from I/R injury.

The present study was undertaken to define whether intracarotid injection of capsaicin induces Fos expression associated with the activation of NOS-containing neurons in brainstem nuclei by combining the immunocytochemical method for Fos with NADPH-d histochemical technique for NOS. The results obtained are as follows: (1) Intracarotid injection of capsaicin caused a significant increase of Fos-like immunoreactive neurons in area postrema (AP), nucleus tractus solitarius (NTS), paragigantocellularis lateralis (PGL) and locus coeruleus (LC), without influence upon the neurons of raphe nuclei (RN) and periaqueductal gray (PAG). (2) NO-containing neurons in PGL and NTS and the double-labeled neurons in PGL were also increased significantly following intracarotid injection of capsaicin. Small numbers of NO-containing neurons were found in LC, but there was no change in the number of NO-containing neurons in RN and PAG. No NADPH-d histochemical activity could be found in AP. (3) The above responses to capsaicin were significantly inhibited by pretreatment with either a capsaicin receptor antagonist ruthenium red or a NMDA receptor antagonist MK-801. The above results indicate that intracarotid injection of capsaicin may activate the neurons in brainstem nuclei involved in cardiovascular regulation, and that NO only plays an indirect role in the modulation of the responses of brainstem nuclei to capsaicin. These effects of capsaicin are mediated by capsaicin receptors with involvement of glutamate.

Objective To examine the effects of genistein ( GST ) on the discharges of neurons in CA1 area of hippocampal slices. Results (1) In response to the application of GST (10, 50, 100 μmol/L; n=48) into the perfusate for 2 min, the spontaneous discharge rates (SDR) of 46/48 ( 95.83 % ) neurons were significantly decreased in a dose-dependent manner. (2) In 9 neurons, the G protein-coupled inwardly rectifying K+ (GIRK) channels antagonist, tetraethylammonium ( TEA 1mmol/L ) completely blocked the inhibitory effect of GST (50 μmol/L). (3) Application of nitric oxide synthase ( NOS ) inhibitor NG-nitro-L-arginine methyl ester ( L-NAME, 50 μmol/L ) into the perfusate for 2 min significantly augmented the SDR of 9/10( 90.0% ) neurons , then GST ( 50 μmol/L ) applied into the perfusate reduced the increased SDR of all 9/9 ( 100% ) neurons. (4) Pretreatment with L-glutamate ( L-Glu, 0.2 mmol/L ) led to a marked increase in the SDR of all 11 ( 100% ) neurons in an epileptiform pattern. The increased discharges were also suppressed significantly after GST (50 μmol/L) was applied into the perfusate for 2 min. Conclusion GST can inhibit the electrical activity of CA1 neurons. The inhibitory effect may be related to the activation of GIRK which induce K+ outward current and then engender the cell membrane hyperpolarization, and to the increased production of NO increase,which indicated that GST play a protective role on the central neurons.